I found why the GPU shows such bad performance (one of the reasons).When running 3D games it enters P0 state (highest performance), when running Miners (CCMiner) it enters P2 state only. Specifically, the core goes to P0 but memory stays at P2, which means the memory never goes past 3000Mhz (6Ghz effective). So you're stuck with +-500hash.

P.S. This is for the GTX 980 obviouslyP.P.S. For whomever is interested - this also makes the card get 7600 Khash in X11 mining without any CCminer tweaks, just 1500core /8000mem settings and +0.075volt